If you want to start a fight on social media, just bring up vaccines. It gets tempers flaring in no time.

One case in point comes from Jan. 8, 2016, when Facebook CEO Mark Zuckerberg posted a picture of himself holding his baby daughter wearing a colorful winter onesie. The caption reads: “Doctor’s visit – time for vaccines!”

To date, the post has earned over 3.4 million comments. Many celebrate Zuckerberg’s personal touch in a public nod toward preventing infectious disease, while others counter that vaccines are a danger to society. Both sides provide lots of graphs, statistics, and name calling in between.

The colorful commentary accompanying this contentious post became the focus of a new study. Published in the journal Vaccine, the study considers how people from either camp express their viewpoints on vaccination.

Researchers examined over 1,400 comments using a linguistic analysis program designed to evaluate text for different emotions, thinking styles, and social concerns.

Both sides expressed similar levels of anger, but the most significant finding was that the pro-vaccine comments were more emotional and fearful, while the anti-vax comments were more logically structured, and tended more toward ideas related to health, biology, research, and science.

According to study co-author Leslie R. Martin, PhD., a researcher specializing in personality and psychosocial predictors of health and mortality risk at La Sierra University in Riverside, CA, it was a “very surprising” outcome.

“What we really expected going in was that the people who are anti-vaccination or who are hesitant would be more inflammatory, much more negative, very emotional, and not demonstrating logical thought processes, and that those on the pro side would be very logical and persuasive in a thoughtful and complex way,” Martin said.

Martin makes clear that this is only a linguistic analysis and not an examination of the facts about vaccination itself.

“What we mean when we say there’s more evidence of analytic thought going on among the anti-vaccination posts is that we’re seeing more of certain kinds of words. They show more tendency to focus on categorical language and formal, precise descriptions. It doesn’t mean that they’re drawing on good science for that, but they are being very precise in the way they are using the language,” she said.

Overconfidence?

Another trend observed in the Facebook commentary is that the pro-vaccine side tended to be more tentative in their responses, while the anti-vaccine side showed more confidence. Although not as statistically significant as the logical language trend, researchers believe the accompanying confidence of the anti-vaccine camp may point to something social scientists call the Dunning Kruger effect. The term is used to describe people who overestimate their competence.

“I think that’s important because when we really understand issues in all of their complexity we recognize we don’t really know things for sure,” Martin said. “Whereas those who are less well informed often times tend be more sure because they don’t recognize they could be wrong.”

Influencing Public Opinion

Insights like these are valuable to health officials intent on influencing public opinion about the safety, efficacy, and necessity of vaccines.

Thanks in large part to the rise of the Internet, an increasing number of parents believe that vaccines carry a higher risk than health officials care to admit. The spread of this notion has had a devastating effect on the public image of vaccination. In some areas, vaccination rates have dropped so far, doctors warn we could see formerly eradicated diseases emerge again.

Those who are less well informed often times tend be more sure because they don’t recognize they could be wrong.

— Leslie R. Martin

Despite the medical community’s efforts to debunk information presented on anti-vaccination websites, these sources can still seed doubt in the minds of parents who consume it. A study from Germany showed that viewing these websites for only 10 minutes or less increased the perceived risk of vaccination, and decreased the perceived risk of vaccine refusal.

This is why researchers are looking so deeply at Facebook comments. If the medical community can understand how vaccine wary parents think, they can be more persuasive in their appeals.

“Providing information by itself is probably fairly futile because it leaves out the emotional component–the fear, anxiety, and suspicion–which seems to be a huge driver,” Martin said. “It’s not just a cost-benefit analysis, devoid of emotion and pre-existing biases.”

Another consideration toward cracking the code of better vaccine compliance is choosing the right voice to deliver the message, as many who are opposed to vaccines already carry a general skepticism for the major players pushing this treatment.

“If we are able to find sources who are at least somewhat immune to the distrust of big pharma and big government, if we can find individuals who aren’t such a point of suspicion, if they make arguments that are well formulated, logical, and analytical, that might actually be quite powerful,” Martin said.

So far, the most effective strategy in getting hesitant parents to vaccinate their children is force. For example, as of June 2016 California eliminated all non-medical vaccine exemptions, effectively mandating that kids must get their shots in order to attend public school. Researchers found even months before the law went into effect that the kindergarten vaccination rate increased 2.5 percent.

Although Martin applauds these types of strong arm measures, she believes appealing to the hearts and minds of the public will be the best strategy in the long run.

“While I support the mandate I also support accompanying that with attempts to sway, educate, and change, so that eventually people aren’t being forced to do something but are doing something because this is the reasonable choice, given what we know,” she said.

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